Trianglify (GitHub) is a SVG background image generator using D3.js, from its name, you will see triangles.

https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpcuPyvPOd2J8ZFfbgCjz9Tc3iy5wIAUYlSDl9hMIGyskz1EEwbklFpytrl68uW7ZDXyuoZk0V6QwyNVH12PAVj4mE5hfvd8DdPkP8kUPct0aPw-i7DE6vHlWMG0jMRCvbFddLI1taVnI/s640/Trianglify.gif

You can set the Noise level, adjust cellsize or cellpadding from the web interface. If you use it as library, there are options like bleed and gradients.

https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSvfxXFlQ1TiKqFwMtYgVmpqzSYzTwVsk60HCgV02ztb6rg_Zdlrldfyoq3_29rvzOY96urOSc-4w1RHjiRH-Ca24EhobY2KRD46_ZFcQxcVqhmdvAEGHAjTNf7ACOPmp6nr1P6mOain8/s640/2014-04-20--12%253A52%253A30.png

In the web, you can save it as SVG file and convert from it. There is also an App by Nick Rowe, Desktop Pattern Generator:

https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsupmvg2vo64pfmuNsUfZUN_MaNFRra_XFWZpxypXAgF9Pb09QgKV6DjkgcmU8IjpL2sqmo_MCli2p6Ayk341fNla_kyAgv-wg2r695Kd5Xb1ux8OthVywN9qqH5evl2Wt6j8Wqk5EgPM/s640/2014-04-20--12%253A52%253A45.png

Whether you are interested in how it generate, you can definitely use is as wallpaper, they look nice and artistic, and the colors are very kind to eyes.

Trianglify is made by Quinn Rohlf under the GPLv3, currently version 0.1.1 (2014-04-16).